1. Field of the Invention
This invention relates to a process for the production of granular detergents/cleaners or components thereof in a mixer used as a granulator with the assistance of a granulation aid.
2. Discussion of Related Art
European patent application 0 264 049 relates to a process for the production of granules by pan granulation in positive mixers and subsequent drying in a fluidized bed, characterized in that the powder-form material to be granulated--optionally formed with standard auxiliaries--is continuously granulated in a high-speed mixer/granulator with the aid of a granulation liquid, preferably water, the product obtained is immediately delivered to a low-speed mixer/granulator for regranulation and is then dried and, at the same time, sprayed with a forming aid, preferably a binder-containing liquid, in a fluidized-bed dryer.
EP-A-0 340 013 describes a granular detergent composition or a component thereof which is characterized in that it has a bulk density of at least 650 g/l and contains 17 to 35% by weight of a non-soap-like surfactant consisting at least partly of an anionic surfactant, 28 to 45% by weight (based on dry matter) of a crystalline or amorphous sodium alumosilicate, the ratio by weight of the alumosilicate to surfactant being 0.9:1 to 2.6:1 and other surfactant components optionally being present to 100% by weight. This composition is obtained by subjecting the above-mentioned surfactant and the above-mentioned alumosilicate both to a stirring motion and to a cutting motion in the presence of a liquid binder in a high-speed mixer/ granulator, but in the absence of particulate auxiliaries to improve the surface properties, granulation and an increase in surface density to at least 650 g/l being achieved.
EP-A-0 352 135 relates to a process for the production of a granular detergent composition or components thereof which have a bulk density of at least 650 g/l, this process comprising the neutralization of a liquid acid precursor of an anionic surfactant with a solid water-soluble alkaline inorganic material and being characterized in that the particulate, solid, water-soluble, alkaline inorganic material is first fluidized with an excess quantity which would be necessary for neutralization, optionally in the presence of at least one other particulate solid, in a high-speed mixer with a stirring and cutting function, an acid precursor is gradually added to the high-speed mixer/granulator at a temperature not exceeding 55.degree. C. and the acid precursor is neutralized with the water-soluble, alkaline inorganic substance while the mixture remains particulate, followed by granulation of the mixture in a high-speed mixer/granulator in the presence of a liquid binder.
EP-A-0 526 978 relates to a process for the production of alkali metal silicate granules in which a 30 to 53% by weight alkali metal silicate solution with an SiO.sub.2 :M.sub.2 O molecular ratio of 1.5:1 to 3.3:1 is converted into granules with a mean diameter of 0.2 to 2 mm in a single drying and granulation step, the silicate solution being introduced into a drum with a plurality of rotating arms at temperatures of 150.degree. C. to 200.degree. C. and a gas, preferably vaporous air, being introduced into the drum at a temperature of about 175.degree. C. to 250.degree. C.
Accordingly, granulation in a mixer/granulator, even in the presence of liquid binders, more particularly in the presence of nonionic surfactants, water or aqueous solutions and gas is known.
A disadvantage in cases where water is used as the granulation aid is that the water either remains completely in the product or has to be at least partly removed again by drying. In the absence of drying, however, the products obtained in most cases are tacky, i.e. no longer flow freely, and cannot be stored. This drying step can again result in "degranulation" and in destruction of the products by friction.
Now, the problem addressed by the present invention was to provide a granulation process which would not have any of these disadvantages and which could be carried out without a subsequent drying step.
According to the invention, the solution to this problem is characterized in that water in its vaporous state is used in a special quantity as the granulation aid.